A semiconductor device such as a CPU used in a portable terminal and the like is a semiconductor element integrated at high density. In such semiconductor device, in order to increase an operating speed, increasing an operating frequency leads to increasing an effective current in proportion to the frequency. Heat is generated by this current, and a temperature of the semiconductor device becomes high. This may cause thermal runaway due to overheat as well as thermal expansion of the semiconductor device and a package surrounding the semiconductor device. For this reason, an improvement of heat dissipation characteristics of the semiconductor device is an important issue for maintaining characteristics of the semiconductor device and prolonging life thereof.
For example, in International Publication No. WO 2011-007510 (Patent Document 1), there is disclosed a heat conductive structure provided with a graphite sheet between a heat sink and a semiconductor package.
In Japanese Patent No. 5641484 (Patent Document 2), the following method is disclosed as a method of forming a graphene thin film. (1) The graphene thin film is formed by mechanically peeling off graphite such as HOPG using Scotch Tape. (2) The graphene thin film is formed by thermal decomposition of SiC. (3) The graphene thin film is formed by performing a carbonization reaction on a transition metal film by chemical vapor deposition. Furthermore, there is disclosed a technique of growing the graphene thin film using a substrate, which is a single crystal substrate on which an epitaxial metal film is formed on an upper surface thereof, and by bringing a carbon material in contact with an upper surface of this epitaxial metal film.